The present invention relates to a sweeping machine that has a hopper for collecting debris removed from a surface and more particularly to a sweeping machine that utilizes recirculated, relatively low pressure air to improve the loading efficiency of the debris hopper especially with light weight litter.
A wide variety of cleaning machines have been known in the past. U.S. Pat. No. 3,304,572 discloses a surface cleaning machine having a hopper divided into a debris collection compartment and a filter compartment. A suction blower draws air from the filter compartment and discharges the air to the ambient atmosphere. A brush is used to sweep debris into the hopper. In using machines of this type for sweeping light debris it has been found that the hopper is often not filled to the degree desired. Instead the portion adjacent the brush tends to clog up. U.S. Pat. No. 1,211,902 discloses a railway track cleander having a duct and double blower arrangement for dust control and recirculation of air. The recirculation of air, with a compression pump through a blast nozzle, is to provide an air blast for loosening the dirt from the roadway. The high pressure blast air requires significant power. This structure does not prevent clogging. Other patents describe similar systems, for example, see U.S. Pat. Nos. 4,006,511; 3,755,851; 2,932,845; 3,872,540. British Pat. No. 808,026 shows a sweeping machine in which air is drawn through a combination filter and debris hopper. An air stream may be directed to a zone adjacent a housed brush. To help prevent debris from escaping to the sides, the debris may be blown toward the center of the brush. This machine also is not particularly suitable for sweeping up light debris and uniformly filling the hopper to the desired degree. In other prior art machines there have been problems encountered due to high air flow requirements with encumbrances on power needs, dust filter concerns and high noise levels. The present sweeping machine overcomes such problems.